Who’s Who in Climate
by Bill Chameides | July 15th, 2010
posted by Erica Rowell (Editor)
Do you have to be an expert to know which way the climate goes?
I am constantly being asked: Is there really a scientific consensus on climate change? Answering objectively is difficult. How do you define a consensus?
Nevertheless, it seems to me there is consensus: Climate change is real, largely caused by humans, and poses serious problems for society. My judgment is based on lots of stuff, not the least of which are statements to that effect from leading scientific organizations such as the U.S. National Academy of Sciences, which was established by Congress in 1863 to advise the nation on scientific and technical issues … such as those surrounding climate change and how to solve it.
But others put less stock in the wisdom and judgment of the National Academy of Sciences, pointing instead to other statements endorsed by hundreds and even thousands of scientists rejecting the notion that the globe is warming and/or that it’s due to human activities or is of any consequence. How, the climate skeptics ask, can there possibly be a consensus when so many scientists say there is not?
How to Resolve a Dispute Between ‘Experts’? Rank Them
One answer often heard is that the scientists signing on to those contrarian statements are not really climate experts, and so their dissenting opinions don’t really count. (Here’s an example.)
To put substance behind that argument, a group of scientists from Stanford University, led by William R. L. Anderegg, assessed the “climate expertise and scientific prominence” of two groups of climate researchers whose names are attached to the most prominent climate change statements: those who subscribe to the tenets of anthropogenic climate change and those who do not. The authors published their results last week in the Proceedings of the National Academy of Sciences.
Substantial Differences Were Found Between the Two Groups of Climate Scientists
From a beginning database of 1,372 climate scientists, the authors focused on 908 researchers who had at least 20 publications as a minimum measure of expertise.
Those meeting this minimum expertise criterion included:
- more than 90 percent of those who accept human-caused climate change, and
- about 20 percent of climate scientists who do accept anthropogenic climate change.
An even greater disparity was found when “the 50 most-published (highest-expertise) researchers from each group” were compared:
- the top-published researchers accepting manmade global warming had an average of 408 climate publications;
- the top-published scientists in the non-accepting camp had an average of 89 publications.
To measure the scientific weightiness of the work, the authors also evaluated the number of times publications were cited by others. Again, a significant disparity:
- the top four papers authored by scientists who subscribe to global warming were cited an average of 133 times;
- the top four papers authored by scientists who do not subscribe to global warming were cited on average 84 times.
The authors concluded:
“We show that the expertise and prominence, two integral components of overall expert credibility, of climate researchers convinced by the evidence of ACC [anthropogenic climate change] vastly overshadows that of the climate change skeptics and contrarians. … Despite media tendencies to present both sides in the ACC debate … not all climate researchers are equal in scientific credibility and expertise in the climate system. This extensive analysis of the mainstream versus skeptical/contrarian researchers suggests a strong role for considering expert credibility in the relative weight of and attention to these groups of researchers in future discussions in media, policy, and public forums regarding anthropogenic climate change.”
In other words:
- There really is consensus among the really good climate scientists.
- The consensus is that climate change is caused by humans and is a serious problem.
The Contrarian Response
Not surprisingly there’s been a quick response to the study in the contrarian blogosphere (see here and here). The primary argument is that the study merely confirms what they’ve been complaining about for years: namely that the climate science community has become a cabal wedded to a flawed scientific analysis (and for some, a sinister political agenda) that has effectively “black-listed” contrarian scientists from publications and grants. The lack of impressive statistics for contrarian scientists is not from a lack of expertise, they argue, but from a lockout.
I don’t buy it. In my experience (which includes an editor position at a major scientific journal), while mistakes are sometimes made in the peer-review process, the contents of peer-reviewed literature are largely determined by quality not the pre-conceived notions of reviewers or editors. Reviewers cannot recommend rejecting a paper simply because they don’t “like” or “agree” with it. Such recommendations must be based on the identification of flawed data, analysis or methods. Frequently reviewers recommend publication of papers whose conclusions they do not subscribe to.
My Reservations About the Study
But I do have some reservations about the paper. For one, I am concerned about the terminology the authors chose to describe the two scientific groups: “convinced by the evidence” for adherents to anthropogenic climate change and in my opinion the somewhat pejorative “unconvinced by the evidence” for the non-adherents to anthropogenic climate change, seemingly denying the possibility that any “evidence” could support the dissenting viewpoint.
I’m also somewhat uncomfortable with the paper’s ad hominem tenor — a seeming attack on the messengers of contrariness rather than on the substance of their arguments.
Still, Dismissing the Paper Would Be a Mistake
But I also know that it is common practice to check someone’s credentials before buying his or her services. In our highly technical world, we as a society must turn to experts on a wide range of issues, and when do, we want to make sure those people really are expert. To do this, we need standards and metrics. And in the science world the metrics include publications and citations.
And at least when it comes to these metrics, Anderegg et al. show fairly convincingly those in the contrarian camp don’t measure up nearly as well as those who support the tenets of anthropogenic climate change. You can choose to ignore that distinction, but before you do, consider this: If you needed an operation, which surgeon would you choose? One with a long and distinguished track record who is ranked in the top tier of doctors or one without such distinctions?
As in many things, when it comes to the climate science marketplace, it’s caveat emptor.filed under: climate change, faculty, global warming, science
and: climate science, climate skeptics, National Academy of Sciences, research